Itchy Red Rash - Dermatology

Itchy Red Rash

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Case 1

Case 1: History 

CC: “She She scratches all night” night 

HPI: 

10 month-old month old girl presents with a 7 month 

history of an itchy itchy red red rash rash involving her face 

and body, which waxes and wanes. 

Her parents report that they bathe her daily and 

use Ivory soap. Sometimes they use Lubriderm 

lotion if her skin appears dry. They recently 

introduced peas into her diet and wonder 

whether this may be contributing to the rash.


PMH: Product of a normal pregnancy and delivery. She is 

otherwise healthy aside from an episode of 

wheezing at 5 months of age. 

No hospitalizations or surgeries. Her 

immunizations are up to date. 

All: NKDA 

Meds: none 

FH: Her mother has asthma and her paternal 

uncle has allergic rhinitis (hay fever). 

SH: She lives in the city with her parents and no pets

Case 1: Exam 

How would 

you describe 

her exam 

findings?

Case 1: Exam 

On exam, 

Gen: well appearing child 

Skin: Erythematous 

ill-defined ill defined 

plaques with overlying 

scale and crust on her 

cheeks and upper eyelids 

(and extensor arms 

though not shown here)

Case 1: Question 1 

What elements in the history are important to 

ask in this case 

a. Which moisturizers are used and where? 

b. Does she scratch or rub her skin? 

c. Does the rash keep her awake at night? 

d. All of the above


Answer: d 

What elements in the history are important to ask in this case 

a. Which moisturizers are used and where? (will give 

you information about distribution. Also, the 

moisturizer may be exacerbating the problem) 

b. Does she scratch or rub her skin? (gives 

information as to whether there is pruritus) pruritus 

c. Does the rash keep her awake at night? (information about 

severity) 

d. All of the above

Case 1: Labs 

You consult pediatric 

dermatology who suggests that 

you get a culture from the site 

of the skin lesions 

The culture obtained from the 

skin of her cheeks reveals 

methicillin 

sensitive Staph Staph 

aureus aureus after 48 hours

Case 1: Differential Diagnosis 

The following is the differential diagnosis of a 

child with an itchy red rash 

 

 

 

 

 

Seborrheic dermatitis 

Atopic dermatitis 

Psoriasis 

Urticaria 

Contact dermatitis


What is the most likely diagnosis given the 

history and physical exam findings? 

a. Seborrheic dermatitis 

b. Atopic dermatitis 

c. Psoriasis 

d. Urticaria 

e. Contact dermatitis


Answer: b 

What is the most likely diagnosis given the history and physical 

exam findings? 

a. Seborrheic dermatitis (less likely to get superinfected, superinfected, 

less 

pruritic) pruritic 

b. Atopic dermatitis 

c. Psoriasis (distribution and morphology does not favor) 

d. Urticaria (would likely be less chronic and form wheals) 

e. Contact dermatitis (no vesicles are present and no 

history of contact with allergens or irritants)

Why Atopic Dermatitis? 

The diagnosis is atopic dermatitis for the following 

reasons: 

 

 

 

 

 

The chronic 

nature of the rash (present x 7 months) 

The distribution 

of the rash (predominantly on the 

cheeks) 

The complaint of pruritus 

(itching) 

The presence of superinfection 

with staph aureus 

Family history of atopic disease


What percentage of children with atopic 

dermatitis also have or will develop asthma or 

allergic rhinitis? 

a. 0-15% 0 15% 

b. 15-30% 15 30% 

c. 30-50% 30 50% 

d. 50-80% 50 80% 

e. 80-100% 80 100%


Answer: d 

What percentage of children with atopic dermatitis also 

have or will develop asthma or allergic rhinitis? 

a. 0-15% 0 15% 

b. 15-30% 15 30% 

c. 30-50% 30 50% 

d. 50-80% 50 80% 

e. 80-100% 80 100%

50 50-80% 80% of 

children with 

A.D. have other 

atopic diseases 

(allergic rhinitis 

or asthma) 

The “Atopic Atopic Triad” Triad 

Atopic 

Dermatitis 

Asthma 

Allergic 

Rhinitis

Atopic Dermatitis: Epidemiology 

 

Affects 10-20% 10 20% of children 

in Western communities! 

Appears to be increasing in 

prevalence 

A.D. begins by 6 months in 

50-66% 50 66% of cases 

A.D. begins by 5 years of 

age in 80-90% 80 90% of cases

Atopic Dermatitis: Basic Facts 

Atopic dermatitis is a skin condition characterized by 

PRURITUS 

The typical distribution varies based on a patient’s patient s age 

 

 

 

Age 2: flexural areas of neck, elbows, knees, wrists, & 

ankles 

Atopic 

dermatitis may clear or present as localized dermatitis 

in adulthood (ie ( ie. . hand eczema, eyelid dermatitis, nipple 

eczema) 

The disease has a chronic relapsing course 

It is associated with other atopic conditions (asthma & 

allergic rhinitis)

Atopic Dermatitis ≠ 

Eczema 

Eczema is a nonspecific term that refers to a 

group of skin conditions with scale and 

inflammation. 

Atopic dermatitis is a specific type of eczematous 

dermatitis.

Typical AD for age < 2 

Age

Typical AD for age > 2 

Age >2: flexural areas of neck, elbows, knees, wrists, & ankles 

On exam, 

In the popliteal fossa 

there are lichenified 

erythematous plaques 

In the antecubital 

fossa, there are many 

erythematous 

excoriated papules 

with overlying crust

Pathogenesis of Atopic Dermatitis 

 

 

 

 

The pathogenesis is incompletely understood 

Atopic dermatitis is usually not triggered by a specific 

allergen 

It results from immune dysregulation 

 

Primarily altered T cell function with skewing towards a T H2 

2 

response 

An altered lipid composition of the stratum corneum 

resulting in a permeability barrier defect contributes and 

may initiate the process (SEE SKIN STRUCTURE 

AND FUNCTION MODULE)

Pathogenesis: Altered T cell Function 

B Cell 

T H 2 

IL-4 IL-5 

Eosinophil 

•In atopic dermatitis, the immune system abnormally favors TH2 helper T cells. 

These cells secrete cytokines, IL-4 and IL-5 

•IL-4 has many functions but is responsible for acting on B cells to make 

them produce IgE preferentially 

•IL-5 also functions to activate B cells, but preferentially activates eosinophils


IgE 

Mast Cell 

B Cell 

T H 2 

IL-4 IL-5 

Eosinophil 

•The B cell under the influence of IL-4 begins making IgE which 

then binds to the surface of mast cells


IgE 

Mast Cell 

Histamine 

Leukotrienes 

B Cell 

T H 2 

IL-4 IL-5 

Eosinophil 

Eosinophil Cationic Protein 

& Major Basic Protein 

•IgE is released in large amounts coating many mast cells which 

when activated by an antigen release histamine, leukotrienes and 

other products that cause vasodilation, edema, and inflammation. 

Meanwhile, eosinophilic granules are released.


IgE 

Mast Cell 

Histamine 

Leukotrienes 

B Cell 

T H 2 

IL-4 IL-5 

Itch & Inflammation 

Eosinophil 

Eosinophil Cationic Protein 

& Major Basic Protein

Pathogenesis: Permeability Barrier Defect 

 

 

Many individuals with atopic 

dermatitis have a defect in 

filaggrin, filaggrin, 

a protein involved in 

barrier formation 

Many have a relative 

deficiency in ceramides 

in the 

stratum corneum. corneum. 

The 

normal stratum corneum 

has 

an equimolar 

ratio of certain 

lipids 

ceramides 

: cholesterol : 

free fatty acids

Back to Case 1

If a biopsy had been 

performed in the 

patient, there would 

be: 

Edema of the 

epidermis (called 

spongiosis”) spongiosis 

Infiltrates of 

lymphocytes and 

some eosinophils 

found in the 

dermis 

Case 1: Biopsy


Which soap brand(s) brand(s) 

would you recommend to 

this patient? 

a. cetaphil 

cleanser 

b. irish 

spring soap bar 

c. dial soap bar 

d. ivory soap bar


Answer: a 

Which soap brand(s) brand(s) 

would you recommend to this 

patient? 

a. cetaphil 

cleanser (liquid cleansers with slightly 

acidic pH and moisturizers are preferred over 

bar soaps) 

b. irish 

spring soap bar (more chemicals and fragrances 

with a pH too basic for the skin) 

c. dial soap bar (see above) 

d. ivory soap bar (see above)

Management: Gentle Skin Care 

 

 

Gentle skin care is important in 

a patient with atopic dermatitis 

as it addresses the permeability 

barrier defect 

Recommendations include: 

Mild soap, as little as 

needed (typically to axillae, axillae, 

groin, and buttock) such as 

Cetaphil ® Cetaphil 

Daily or twice daily 

application of ointments & 

creams (better than lotions)

Management: Control Inflammation 

 

Currently, the first-line first line of therapy is topical 

corticosteroids 

Corticosteroids work in this case primarily 

through addressing the dysregulated 

T cell 

function by downregulating 

T cells


What is the most likely corticosteroid you would 

choose for this patient’s patient s facial lesions? 

a. clobetasol 

ointment 

b. lidex 

ointment 

c. TAC ointment 

d. hydrocortisone ointment 

e. clobetasol 

cream 

f. hydrocortisone cream


Answer: d 

What is the most likely corticosteroid you would 

choose for this patient’s patient s facial lesions? 

a. clobetasol 

ointment (too strong for the face) 

b. lidex 

ointment (too strong for the face) 

c. TAC ointment (too strong for the face) 

d. hydrocortisone ointment 

e. clobetasol 

cream (too strong for the face) 

f. hydrocortisone cream (not as much penetration as 

ointment)

Topical Corticosteroids Review 

Super-High Super High Potency: Clobetasol 

(Temovate Temovate) ) 0.05% cream, 

ointment, solution, foam 

High Potency: Fluocinonide 

(Lidex Lidex) ) 0.05% cream, gel, 

ointment, solution 

Medium Potency: Triamcinolone 

(TAC) 0.1% cream, 

ointment, solution 

Mid-Low: Mid Low: Aclometasone(Aclovate) Aclometasone(Aclovate) 

0.05% cream or 

ointment, Desonide 

0.05% cream or ointment 

Lowest Potency: Hydrocortisone 1% or 2.5% cream or 

ointment 

NOTE: Clobetasol 

0.05% is STRONGER than 

hydrocortisone 1%. Look at class not percentage.


 

 

 

Ointments are preferred over creams 

Low potency is usually effective for the face (e.g. 

Hydrocortisone 1-2.5% 1 2.5% ointment) 

Body and extremities often require medium 

potency (e.g. TAC 0.025 to 0.1% oint.) oint.)


 

If topical therapies fail, you can target T 

cells with systemic therapies: 

 

 

Ultraviolet light therapy 

Systemic immunosupressive 

therapies such as 

Mycophenolate 

mofetil, mofetil, 

cyclosporine, 

methotrexate… 

methotrexate 

HOWEVER, you should not “go go there” there 

until the patient’s patient s atopic dermatitis is 

optimally managed otherwise


What percentage of atopic dermatitis patients 

are colonized with staph aureus? aureus 

a. 10% 

b. 30% 

c. 50% 

d. 70% 

e. 90%


Answer: e 

What percentage of atopic dermatitis patients 

are colonized with staph aureus? aureus 

a. 10% 

b. 30% 

c. 50% 

d. 70% 

e. 90%

Management: Treat Infection 

 

 

 

 

 

90% of AD patients can be chronic 

staph carriers 

In atopic dermatitis, Staph aureus 

& 

Group A Strep 

superinfections 

are 

common 

Superinfections 

act as a trigger for flares 

of atopic dermatitis & stimulate 

inflammation 

In cases of superinfection, superinfection, 

a course of 

SYSTEMIC antibiotics is 

recommended 

Patients may also develop viral 

infections including: herpes simplex, 

warts & molluscum contagiosum

Staph Aureus 

Superinfection 

On exam, patient has 

excoriated papules on the 

chin as well as erythematous 

plaques around the eyes 

bilaterally with overlying 

yellow crusting (impetigo)

Management: Antihistamines 

Antihistamines help 

to break the 

itch/scratch cycle 

Standing night-time night time 

dose of sedating 

antihistamine such as 

Diphenhydramine 

(Benadryl ® ) or 

Hydroxyzine 

(Atarax Atarax ® ) is helpful

Management Summary: 4 Key Factors 

1. 

2. 

3. 

4. 

• 

• 

• 

• 

Gentle skin care: Avoid irritation and try to improve 

barrier 

Avoid harsh soaps, hot water and use emollients 

frequently 

Control inflammation 

Topical antiinflammatory 

agents) 

Control itch 

Oral antihistamines at night 

Treat infection, if present 

Course of SYSTEMIC antibiotics

Recommendations for 

Case 1

Pediatric Dermatology Recommendations in this case 

 

 

 

 

 

 

 

Use as little soap as needed to remove dirt 

 

Use “syndet syndet” soaps which have slighly 

acidic pH that mimics 

natural skin such as Cetaphil ® cleanser 

Aquaphor ® BID everywhere 

Triamcinolone 

0.1% ointment to body BID 

Hydrocortisone 2.5% ointment to face BID 

Keflex 

po 

Atarax 

1 tsp po QHS 

F/U in 2 months

Case 2


HPI: 12 yo 

boy presents with the sudden onset of lesions all 

over his face. He tried to use the topical hydrocortisone he 

uses for his atopic dermatitis but it did not help. 

PMH: atopic dermatitis, asthma 

All: allergic rhinitis 

Meds: albuterol, albuterol, 

topical hydrocortisone 

FH: both parents had a history of atopic dermatitis as 

children 

SH: lives with his mother and father and sister. His mother 

has a recent “cold cold sore” sore 

ROS: negative

Case 2: Exam 

On exam, 

VS: T-100.4, HR-80, BP-110/70, 

RR-14, O2sat 100% 

Skin: diffuse erythematous 

vesicles some with yellow 

overlying crust particularly on the 

upper forehead


What is the most appropriate immediate 

treatment? 

a. topical hydrocortisone and benadryl 

b. epinephrine IM 

c. acyclovir 

d. none of the above, the process is self-limited self limited


Answer: c 

What is the most appropriate immediate 

treatment? 

a. topical hydrocortisone and benadryl 

b. epinephrine IM 

c. acyclovir 

d. none of the above, the process is self-limited self limited

Diagnosis: Eczema Herpeticum 

The diagnosis in this case is eczema herpeticum 

which is most frequently seen in young children 

and associated with HSV 

 

Recurrences may occur 

It is characterized by the sudden appearance of 

vesicular, pustular, pustular, 

and crusted lesions 

Secondary staph infection is common 

Treatment typically involves systemic antivirals 

and antibiotics directed against staph aureus

Case 3


HPI: 5 yo 

girl is brought in by her father who is 

concerned about the “white white spots” spots she is developing on 

her face 

PMH: asthma 

All: none 

Meds: albuterol 

FH: mother has atopic dermatitis, father has asthma 

SH: lives at home with her mother and father 

ROS: negative

Case 3: Exam 

On exam, 

Gen: well appearing 

Skin: poorly 

marginated, 

hypopigmented, 

slightly scaly patches 

on the cheeks

Case 3: Labs 

Suspicious of an fungal infection, you perform a 

KOH preparation and find that that is is 

negative - there are no hyphae


What is the most likely diagnosis? 

a. pityriasis alba 

b. vitiligo 

c. tinea versicolor 

d. psoriasis


Answer: a 

What is the most likely diagnosis? 

a. pityriasis alba 

b. vitiligo (lesion would be depigmented, depigmented, 

with 

no pigment at all) 

c. tinea versicolor 

(blunt hyphae 

would have been seen) 

d. psoriasis (would expect to see plaques and erythema) 

erythema

Diagnosis: Pityriasis Alba 

Form of subclinical dermatitis frequently atopic in 

origin, often asymptomatic 

 

Found more commonly in darker skinned children 

Presents as poorly marginated, marginated, 

hypopigmented, hypopigmented, 

slightly 

scaly patches on the cheeks 

Typically found in young children, often presenting in 

Spring and Summer when the normal skin begins to tan 

Low potency topical steroids and emollients are the 

treatment of choice

Take Home Question 

Which of the following is most likely to be effective 

as a strategy for managing childhood atopic 

dermatitis? 

a. find the allergen(s) allergen(s) 

causing the disease 

b. avoid all seafood, nuts, eggs, and soy 

c. avoid steroids stronger than hydrocortisone 

to avoid toxicity 

d. combination therapy aimed at moisturizing, 

treating inflammation, itch, and infection.

Take Home Question 

Answer: d 

Which of the following is most likely to be effective 

as a strategy for managing childhood atopic 

dermatitis? 

a. find the allergen(s) allergen(s) 

causing the disease 

b. avoid all seafood, nuts, eggs, and soy 

c. avoid steroids stronger than hydrocortisone 

to avoid toxicity 

d. combination therapy aimed at moisturizing, 

treating inflammation, itch, and infection.

END OF MODULE

Itchy Red Rash - Dermatology

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